日志
HC-SR04超聲波測距
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#include <reg51.h>
#define uchar unsigned char
#define uint unsigned int
#define ulong unsigned long
extern void cs_t(void);
extern void delay(uint);
extern void display(uchar*);
//data uchar display(uchar*);
data uchar testok;
void main (void)
{
data uchar dispram[5];
data uint i;
data ulong time;
P0=0xff;
P2=0xff;
TMOD=0x11;
IE=0x80;
while (1)
{
cs_t();
delay(1);
testok=0;
EX0=1;
ET0=1;
while(! testok) display(dispram);
if (1==testok)
{
time=TH0;
time=(time<<8)| TL0;
time*=172;
time/=10000;
dispram[0]=(uchar) (time%10);
time/=10;
dispram[1]=(uchar) (time%10);
time/=10;
dispram[2]=(uchar) (time%10);
dispram[3]=(uchar) (time/10);
if (0==dispram[3]) dispram[3]=17;
} else
{
dispram [0]=16;
dispram [1]=16;
dispram [2]=16;
dispram [3]=16;
}
for (i=0;i<300;i++) display(dispram);
}
}
void cs_r(void) interrupt 0
{
TR0=0;
ET0=0;
EX0=0;
testok=1;
}
void overtime(void) interrupt 1
{
EX0=0;
TR0=0;
ET0=0;
testok=2;
}
NAME CS_T
?PR?CS_T?CS_T SEGMENT CODE
PUBLIC CS_T
RSEG ?PR?CS_T?CS_T
CS_T: PUSH ACC
MOV TH0, #00H
MOV TL0, #00H
MOV A, #4D
SETB TR0
CS_T1: CPL p1.0
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
DJNZ ACC,CS_T1
POP ACC
RET
;
END
name delay
?pr?_delay?delay segment code
public _delay
rseg ?pr?_delay?delay
_delay: push acc
mov a,r7
jz dela1
inc r6
dela1: mov r5,#50d
djnz r5, $
djnz r7,dela1
djnz r6,dela1
pop acc
ret
end
NAME DISPLAY
?PR?_DISPLAY?display segment code
?co?_DISPLAY?display segment data
EXTRN CODE (_DELAY)
PUBLIC _DISPLAY
RSEG ?CO?_DISPLAY?DISPLAY
?_display?byte:
dispbit: ds 1
dispnum: ds 1
rseg ?pr?_display?display
_display: push acc
push dph
push dpl
push psw
inc dispnum
mov a,dispnum
cjne a,#4d,disp1
DISP1: JC DISP2
MOV DISPNUM,#00H
MOV DISPBIT,#0FEH
DISP2: MOV A,R1
ADD A,DISPNUM
MOV R0,A
MOV A,@R0
MOV DPTR,#DISPTABLE
MOVC A,@A+DPTR
MOV P0,A
MOV A,DISPNUM
CJNE A,#2D,DISP3
CLR P0.7
DISP3: MOV P2,DISPBIT
MOV R5,#00H
MOV R7,#0AH
LCALL _DELAY
MOV P0,#0FFH
MOV P2,#0FFH
MOV A,DISPBIT
RL A
MOV DISPBIT,A
POP PSW
POP DPL
POP DPH
POP ACC
RET
DISPTABLE: DB 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H,88H,83H,0C6H,0A1H,86H,8EH,0BFH,0FFH
END
